Sudden-stop brake-light warning system

ABSTRACT

A sudden-stop brake-light warning system (10) that causes the brake lights (56) of a vehicle to intermittently pulsate. The pulsation of the lights (56) is achieved by a flashing brake-light circuit (12) that is only activated when the brake pedal is depressed during a panic stop. The circuit (12) consists of a mercury switch (51), located in an inertia operative switching circuit (16), that closes only when the brake switch (54) is depressed during a panic stop. When the switch (54) closes, the power from the vehicle battery (52) is applied to the gate of a silicon controlled rectifier (CR1) located in a silicon controlled rectifier circuit (18). The energizing of CR1 enables a multivibrator circuit (14) connected via a relay driven transistor (Q3) to the coil (20A) of a relay (K1) located in a relay drive/relay circuit (20). The relay is pulsed in accordance with the time constant of the multivibrator and as the coil (20A) pulses, so are the brake lights (56).

TECHNICAL FIELD

The invention pertains to the general field of brake lights as used onvehicles such as automobiles and trucks and more particularly to suchbrake lights that flash intermittently during a sudden or panic stop.

BACKGROUND ART

It has long been known that intermittently flashing lights attract moreattention than lights that illuminate constantly. This is particularlytrue in automobiles where currently, the turn indicating lights in boththe front and back flash intermittently to warn and alert drivers of animpending left or right turn. However, even though flashing lights aremore noticeable, they are not employed with vehicle brake lights. Thebrake lights in current use, conventionally remain continuouslyilluminated as long as the brake light switch remains closed by thecontinuous pressure applied to the brake pedal.

The conventional brake light circuit which operates a pair of lightslocated at the rear of a vehicle has in many instances failed to produceadequate warning. This problem is especially prevalent on newer vehiclesthat have a large assemblage of lights on the rear panel of the vehicle.In addition, turn signals which are normally located in the same lightassembly with the taillights and stoplight often add to the confusion asto whether brakes are being applied or a turn is to be made.

One of the problems in driving is that to drive safely, a driver needsto know how quickly the automobile in front is slowing down withconventional brake lights, an illuminated light only-means that thedriver has his or her foot on the brake pedal. The trailing driver doesnot know if the vehicle is decelerating slowly or whether a sudden panicstop is about to take place. The brake light used in conventionalvehicles looks the same in either case.

With vehicles traveling at high speeds on interstate and freeway roadsystems with relatively little spacing between vehicles; the ambiguityin brake lights can and has caused rear end collisions with consequentvehicular damage, human injury, loss of life and further roadcongestion.

A search of the prior art did not disclose any patents that readdirectly on the claims of the instant invention however, the followingU.S. patents were considered related:

    ______________________________________                                        U.S. PAT. NO. INVENTOR    ISSUED                                              ______________________________________                                        5,059,947     Chen        22 October 1991                                     4,663,609     Rosario     5 May 1987                                          3,593,278     Bower       13 July 1971                                        3,528,056     Voevodsky   8 September 1970                                    ______________________________________                                    

U.S. Pat. No. 5,059,947 issued to Chen, discloses a vehicle brakewarning device for use in a vehicle with a brake pedal. The deviceincludes a detector for producing different electrical signals inresponse to the magnitude of the inertia force experienced duringbraking. Whenever a pressing force is exerted on the brake pedal, thedetector experiences an inertia force whose magnitude depends upon thespeed of the vehicle. The detector sends an appropriate signal dependentupon the magnitude of the inertia force to a control circuit which thenactivates a warning device which activates the brake lights.

U.S. Pat. No. 4,663,609 issued to Rosario discloses a brake lightwarning system for a motor vehicle which causes the brake lights toflash in a manner to attract the attention of a driver to the rear ofthe vehicle. The system provides a warning of a slow down or stopping ofthe vehicle upon the application of the brakes. The brake lights arefirst caused to flash rapidly for 2 or 3 times for a first interval oftime followed by prolonged "on" periods interrupted periodically by ashort "off" period followed by a short "on" period followed by a short"off" period for a second interval of time as long as pressure isapplied to the brake pedal of the vehicle.

U.S. Pat. No. 3,593,278 issued to Bower discloses a vehicle brake lightsystem wherein a flashing signal of variable frequency indicates therate of deceleration of a vehicle. The system includes a series ofinertia switches and resistors forming a decelerometer, a multivibratorand a transistorized gate circuit which flashes the brake lights at afrequency proportional to the detected rate of deceleration.

U.S. Pat. No. 3,528,056 issued to Voevodsky discloses a device formeasuring the deceleration of a leading vehicle. The device uses anaccelerometer formed by mercury switches tilted at different angles withrespect to a horizontal. They are progressively closed as thedeceleration increases. In another form, deceleration is measured bybrake pressure and in still another form a tachometer device is coupledto a rotating part of the automobile. The warning light, mounted on theleading car, is flashed at a rate which varies exponentially with acomponent of deceleration.

For background purposes and as indicative of the art to which theinvention relates, reference may be made to the following remainingpatents found in the search:

    ______________________________________                                        U.S. PAT. NO. INVENTOR    ISSUED                                              ______________________________________                                        4,983,953     Page        8 January 1991                                      4,403,210     Sullivan    6 September 1983                                    3,559,164     Bancroft    26 January 1971                                     3,382,405     Johnson     7 May 1968                                          ______________________________________                                    

DISCLOSURE OF THE INVENTION

The sudden-stop brake-light warning system provides a driver in avehicle following another vehicle with a positive warning signal thatthe front vehicle is about to make a sudden stop. The warning isprovided by the brake lights that have been modified by the system tointermittently flash when such a "panic" stop is about to be made.

The system employs a flashing brake light circuit that does notinterfere with the existing vehicle brake-light circuit. The inventivecircuit becomes operational only if the driver depresses the brake pedalto make a sudden or panic stop. In this occurrence, the brake lightsbegin to flash intermittently to provide a positive and explicitwarning.

In the preferred embodiment, the flashing brake-light circuit consistsof four major elements: a multivibrator that sets the pulse rate of theblinking lights; a silicon controlled rectifier (SCR) circuit thatenables the multivibrator when a panic stop occurs. The SCR has its gateconnected to an inertia operative switching circuit that employs amercury switch. The other conductive side of the mercury switch isconnected to the vehicle battery via the brake pedal activated brakeswitch. The mercury switch is located in a sloping attitude so that bothinertia and gravity can be utilized to control the sensitivity of theswitch. The output of the multivibrator is applied to a relay drivetransistor located in a relay drive/relay circuit, that drives asingle-pole double-throw relay.

When the multivibrator is disabled and the brake switch is normallydepressed, the power from the vehicle battery is applied through thenormally closed contact of the relay onto at least one of the brakelights. However, when the multivibrator is enabled, the relay drivertransistor pulses the coil of the relay causing the normally closedcontacts pulsate in accordance with the time constant of the enabledmultivibrator. Thus, the brake lights are caused to flash ON and OFF toprovide the panic stop warning.

In view of the above disclosure, it is the primary object of theinvention to include a vehicle a crash deterrent safety feature thatprovides a tailgating driver, with more time to react to a sudden orpanic stop to thus avoid incidents of rear end collisions.

In addition to the primary object, it is also an object of the inventionto provide a system that:

utilizes the existing brake light circuit of a vehicle and that can addadditional lights, connected in parallel, to the front or side of thevehicle;

allows both brake lights to flash simultaneously to avoid confusion withleft and right turn indicators,

does not interfere with the existing brake-light circuit or any othervehicle electrical system;

is reliable, requires minimum maintenance and is fail safe in operation;

is relatively simple in design and is substantially easy to install inany type of vehicle including automobiles, trucks, buses andmotorcycles;

produces a flashing light which is substantially universally recognizedas being a caution or hazard signal.

These and other objects and advantages of the present invention willbecome apparent from the subsequent detailed description of thepreferred embodiment and the claims taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of the sudden-stop brake-light warning systemattached to the existing vehicle brake-light circuit.

FIG. 2 is a schematic diagram of the sudden-stop brake-light warningsystem attached to the existing vehicle brake-light circuit.

FIG. 3 is a side elevational view of a mercury switch that is set to therequired slope angle by means of its electrical leads.

FIG. 4 is a side elevational view of a housing into which is inserted amercury switch and which has a tab that allows the housing to befastened to a structure of the required slope angle.

BEST MODE FOR CARRYING OUT THE INVENTION

The best mode for carrying out the sudden-stop brake-light warningsystem 10 is presented in terms of a preferred embodiment that isdesigned to provide a trailing driver with a visual warning that thevehicle in front is in the process of making a sudden stop.

The preferred embodiment as shown in FIG. 1 through 4 is comprised ofthe following major elements: a flashing brake-light circuit 12 thatfurther consists of a multivibrator circuit 14, an inertia operativeswitching circuit 16, a silicon controlled rectifier circuit 18 and arelay drive/relay circuit 20. The circuit 12 operates in combinationwith an existing vehicle brake-light circuit 50 consisting of a powersource typically a vehicle battery 52, a brake pedal operated brakeswitch 54 connected between the power source and at least one brakelight 56.

The system 10 is designed to function in two operational modes: a normalbrake-light mode and a flashing brake-light mode.

The normal mode uses the existing brake-light circuit 50 that bypassesthe flashing brake-light circuit 12. In this normal mode, when the brakepedal is normally depressed, the current path as shown in FIG. 2, isfrom the vehicle battery 52 through the brake pedal operated brakeswitch 54 through the pole 20B and normally closed contact 20C of arelay K1 that is located in the relay drive/relay circuit 20. The relayK1 is preferably comprised of a 12-volt relay that is powered by thevehicle's 12-volt battery 52. From the relay contact 20C, the current isapplied directly to illuminate at least one brake light 56.

The flashing brake-light mode becomes operational only when the brakepedal is suddenly depressed such as in a "panic" stop. In this case, theflashing brake light circuit 12 is automatically connected into thecircuit path of the brake lights 54 as shown in block form in FIG. 1 andschematically in FIG. 2. Each element of the circuit 12 is nextdescribed with reference to FIGS. 1 and 2.

The multivibrator circuit 14 is configured as a flip-flop typeconsisting of a pair of cross connected NPN transistors Q1 and Q2preferably of the 2N2222 type. The circuit 14 is normally inoperativeand can only be enabled when the inertia operative switch 16 closeswhich only occurs during a panic stop. When the switch 16 closes, asilicon controlled rectifier CR1 is turned on which then enables themultivibrator 14 as described infra. When the circuit 14 is enabled thetransistors continuously switch alternatively from a conducting state toa nonconducting state to generate a pulse output that is applied throughoutput resistor R5 to the relay drive/relay circuit 20 also describedinfra.

The collectors of transistors Q1 and Q2 as shown in FIG. 2, areconnected to resistor-capacitor networks 14A and 14B. The time constantsof these networks are identical and are determined by capacitor C1 andresistor R1, and capacitor C2 and resistor R2 respectively. The tworesistor-capacitor networks 14A, 14B alternatively charge and dischargeat a frequency determined by the time constant of the networks and thefrequency is equal to 1/(C1*R1+C2*R2). This frequency which determinesthe flashing rate of the lights 56, can be set to range between 2 Hertzand 3 Hertz by the proper selection of capacitor C1 and resistor R1, andcapacitor C2 and resistor R2.

The enabling and disabling of the multivibrator circuit 14 is providedby the silicon controlled rectifier circuit 18. The circuit 18 includesa 2N5061 silicon controlled rectifier (SCR) CR1 which requires verylittle current to be turned on. If an SCR is not included in the circuit18, the multivibrator 14 will turn-on for only a brief time(approximately two seconds). This time period is insufficient to alertthe driver of a tailgating vehicle. The SCR has its gate 18A connectedthrough resistor R6 to the second contact B of the inertia activatedswitch 51 located in the inertia operative switching circuit 16, and itsanode connected to the emitter of transistor Q1 and Q2 in themultivibrator circuit 14. Under normal conditions the gate 18A or CR1 isOFF and the ground/bypass circuit connected to the cathode of CR1 keepsthe multivibrator disabled by maintaining the emitters of Q1 and Q2grounded. When the brake pedal is suddenly depressed such as in a panicstop, the brake switch 54 closes and the sudden jarring of the vehiclecaused by the panic stop causes the inertia switch 51 to close. Theswitch 51, which in the preferred embodiment consists of a mercuryswitch as shown in FIGS. 3 and 4, has a first contact A and a secondcontact B. The first contact A is connected to the positive terminal ofthe vehicle battery 52 through the brake switch 54. With the mercuryswitch 51 closed, the positive voltage from the battery 52 is appliedthrough resistor R6 to the gate 18A of the SCR CR1. Upon the applicationof this positive voltage, the gate opens, the SCR is turned ON and themultivibrator circuit is enabled.

The output of the enabled multivibrator circuit is applied throughresistor R5 to the base of a relay driver 2N2222 NPN transistor Q3located in the relay drive/relay circuit 20, the emitter of transistorQ3 is in a common connection with the emitters of transistors Q1, Q2 inthe multivibrator and the Q3 collector is connected directly to one sideof the coil 20A of relay K1. The direct output current of themultivibrator 14 is insufficient to energize the coil of the relay K1.Therefore, transistor Q3 is used to increase the current to allow therelay K1 to be energized. The other side of the relay coil is connectedto the relay's pole 20B which is also in line with the normalbrake-light circuit 50. Thus, as previously mentioned, under normalbraking conditions, the multivibrator circuit 14 is disabled and therelay, through contact 20C, allows the brake lights 56 to illuminate.However, with the multivibrator circuit 14 enabled, the relay is causedto oscillate in synchronization with the time constant provided by themultivibrator allowing the lights 56 to rapidly flash ON and OFF duringthe time period that the multivibrator is enabled.

The sensitivity of the flashing brake-light circuit 12 is primarilydependent on the energizing speed of the mercury switch 51. In practice,this switch S1 is attached to the inertia-operative switching circuit 16with a means for allowing the switch to be placed in a selective slope φwith respect to the vehicle's horizontal plane. Through testing, it wasdetermined that the slope best suited for this application is between 25and 30 degrees with the switch's conductive base end 16A located higherthan its front end 16B. With this configuration, the relationshipbetween inertia and gravity is utilized to close the electrical leads inthe conductive end at an optimum time.

Two mercury switch attachment schemes can be utilized to set therequired switch slope φ. The preferred method is to bend the electricalleads 16C as shown in FIG. 3 and then move the switch to the selectedslope. Alternatively, as shown in FIG. 4, a housing 16D may be employedinto which is inserted the switch S1 with its electrical leads extendingfrom the back of the housing. At the back end of the housing is anoutwardly extending side tab 16E that is attached, by means of afastener 16F, to a structural member on the vehicle near the system 10.

The system primarily is designed to operate with the conventional rearbrake lights 56 of a vehicle. However, the system may also be operatedwith a second set of at least one brake light 58 connected in parallelwith at least one brake light 56 as shown in FIGS. 1 and 2. This secondset of lights 58 may be add-ons attached to the front of the vehicle orthey may be comprised of the vehicle's front right and left turninglights. In either case, the additional set of blinking light addsanother degree of safety to the vehicle.

While the invention has been described in complete detail andpictorially shown in the accompanying drawings, it is not to be limitedto such details, since many changes and modifications may be made in theinvention without departing from the spirit and scope thereof. Hence, itis described to cover any and all modifications and forms which may comewithin the language and scope of the appended claims.

We claim:
 1. A sudden-stop brake-light warning system that functions incombination with an existing vehicle brake-light circuit comprising apower source, a brake pedal operated brake switch connected between thepower source and at least one brake light, said system comprising:a) aflashing brake-light circuit comprising:(1) a multivibrator circuit, (2)an inertia-operative switching switch circuit that includes aninertia-activated switch having a first contact A connected to the powersource through the brake switch and a second contact B, (3) a siliconcontrolled rectifier circuit that includes a silicon controlledrectifier having its gate connected to the second contact B of saidinertia-activated switch and its anode connected to said multivibratorcircuit, (4) a relay drive/relay circuit connected to the output of saidmultivibrator circuit, whereupon the closing of said inertial-activatedswitch, due to a panic stop of a vehicle, the current from the powersource turns ON said silicon controlled rectifier which then enablessaid multivibrator circuit which in turn, applied a pulsating current toa coil of a relay located in said relay drive/relay circuit causing saidrelay to pulsate a normally closed contact of said relay causing said atleast one brake light to rapidly flash ON and OFF in accordance with thepulsating current set by a time constant in said multivibrator circuit,and b) wherein said existing vehicle brake-light circuit under normalbraking conditions, provide means for bypassing said flashing brakelight circuit to allow the power source to be applied directly to saidat least one brake light through the normally closed contact of saidrelay.
 2. The system as specified in claim 1 wherein said multivibratorcircuit comprising a flip-flop which consists of a pair ofcross-connected transistors that continuously switch alternatively fromconducting to nonconducting, generating a pulse output that energizessaid relay.
 3. The system as specified in claim 1 wherein saidinertia-activated switch is comprised of a mercury switch.
 4. The systemas specified in claim 3 wherein said mercury switch is attached to saidinertia-operative switching circuit with selecting slope means forallowing said switch to be placed in a selective slope with respect tothe vehicle's horizontal plane with the conductive base end of saidswitch located higher than its front end so that the relationshipbetween inertia and gravity is utilized to close electrical leads in theconductive base end.
 5. The system as specified in claim 4 wherein saidmercury switch is sloped at angle between 25 and 30 degrees.
 6. Thesystem as specified in claim 5 wherein said selecting slope means forsaid mercury switch is provided by the electrical leads extending fromthe conductive base end of said mercury switch.
 7. The system asspecified in claim 5 wherein said selecting slope means for said mercuryswitch comprises a housing into which is inserted said mercury switchwith its electrical leads extending form the back of said housing, saidhousing further having an outwardly extending side tab that attaches bymeans of a fastener to a structural member on the vehicle near saidsystem.
 8. The system as specified in claim 1 wherein said power sourceis comprised of the vehicle's 12-volt battery.
 9. The system asspecified in claim 1 wherein said relay in said relay drive/relaycircuit comprises a 12-volt relay that has its pole connected to therelay coil.
 10. The system as specified in claim 1 further comprising asecond set of at least one brake light connected in parallel with saidat least one brake light and located on the front section of saidvehicle.
 11. The system as specified in claim 10 wherein said second setof at least one brake light is comprised of the vehicle's front rightand left turning lights.